


Polyjuice and Love Songs

by FantasticNumberNine



Series: John Watson and the Chamber of Secrets [8]
Category: Harry Potter - J. K. Rowling, Sherlock (TV)
Genre: AU, Christmas Holidays, Crossover, Gen, Hints of sherstrade, Polyjuice Potion, Polyjuice potion fail, Potterlock, Sherlock Has A Crush, Tom Riddles diary, and it's mysterious properties, but it's not john, poet!sherlock, valentines day, yet - Freeform
Language: English
Status: Completed
Published: 2014-09-06
Updated: 2014-09-06
Packaged: 2018-02-16 09:30:51
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,809
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2264592
Author URL: https://archiveofourown.org/users/FantasticNumberNine/pseuds/FantasticNumberNine
Summary: <blockquote class="userstuff">
              <p>The boys find out that Moriarty is not the one opening the Chamber of Secrets, and stumble on a mysteriously blank, fifty year old, diary. A diary that claims Hagrid opened the Chamber fifty years ago.</p>
            </blockquote>





	Polyjuice and Love Songs

**Author's Note:**

> *disclaimer*
> 
> I have decided that whenever Mycroft thinks Greg is too annoying, he'll hex his hair into neon pink feathers. Which is an amusing image.

The double attack on Henry and Nearly Headless Nick sent the castle into panic, with Nick's attack curiously causing the most worry. After all, what was powerful enough to harm someone who was already dead? There was a mad dash for nearly everyone to leave the castle for Christmas, which suited John just fine--he was sick of everyone scurrying around him in the corridors.

"Make way for the Heir of Slytherin, seriously evil wizard coming through!"

Well, almost everyone. Fred and George seemed to find John's pariah status deeply amusing.

"This is _not_ a laughing matter!"

"Oh, get out of the way, Percy, John's in a hurry!" Fred pushed his older brother aside.

"Yea, he's nipping off to the Chamber of Secrets for a cup of tea with his fanged servant!" George chortled, an arm around John.

John honestly didn't mind when the twins would ask him loudly who his next victim would be, or lobbed cloves of garlic at him in the Great Hall; Fred and George at least seemed to think his being the Heir was quite ludicrous. Their antics seemed to aggravate Jim Moriarty too, who looked increasingly frustrated each time John pretended to consider a next victim or shook 'holy water' from his mess of hair.

"Obviously, he's jealous you're getting all the credit--course, he can't really come out and say it's _him_ , but it's got to really burn him that people think it's _you_ ," Greg said knowingly.

"We'll know soon enough," Mycroft said smoothly, picking out an almond dusted croissant from a tray of pastries. "The Polyjuice Potion is nearly ready for consumption."

The holiday found John, Greg and Mycroft sharing Gryffindor tower with just the twins and Percy (Sherlock having stomped out to the train without so much as a 'Happy Christmas' to Mycroft), but Percy seemed unable to tolerate his brothers for very long and avoided their common room as much as he was able.

John and Greg were woken at dawn by Mycroft bursting back into their dormitory fully dressed and disgustingly awake.

"Wake up! The potion is ready, and if you're truly set on doing this, I think we should do it tonight--"

"Happy Christmas to you too, Mycroft--oi, John!"

John groaned, burying himself deeper into his covers and hiding under his pillow.

"Go 'way..."

Someone jumped on his bed.

"I know this is only your second Christmas, but I promise it'll be even better than last year--you've just got to get up first!"

And then Greg ripped back John's blankets to let in the pre-dawn chill that was inescapable when living in a castle.

"Hey!" John threw his pillow in Greg's general direction and missed completely, Greg laughing all the while.

"Christmas, John! Get up!"

"The sun's not even out, Greg!"

"I see what you meant, Gregory. He's altogether worse than I thought," said Mycroft, sounding far too dramatically woeful for whatever time of the morning it was.

"We've got our work cut out for us," Greg grinned around a mouthful of fudge and tossed one of John's presents at him.

John decided he may just enjoy Christmas after all as he went down to dinner with Mycroft and the Lestrade's, all of them wearing hand knit jumpers made by Greg's mother. He knew he would forever treasure the sight of Mycroft in his periwinkle blue jumper with a large gold 'M' on the front--and the altogether ridiculous blush he'd gotten when Greg informed him he was a proper member of the Lestrade family now.

The Christmas feast was even better than John remembered, and John sang along with as many Christmas carols as he could. Mycroft looked like a normal thirteen year old for once, giggling like a small child when Fred and George changed Percy's Prefect badge to say 'Pinhead' instead. 

And everyone ignored Moriarty's snide comments about their jumpers over at the Slytherin table--John and Greg figured he'd be getting his comeuppance soon enough, and Mycroft had simply decided not to care, digging eagerly into the first servings of pudding.

To Greg's credit, he was able to hold in his laughter until after they'd left Mycroft in the Hospital Wing, ducking into the first empty classroom to collapse, guffawing uproariously.

" _Myc's got a tail_!"

John's composure crumbled as he dropped next to Greg, a hand over his mouth as he giggled uncontrollably.

" _And his ears_!"

Mycroft was confined to the hospital until the beginning of February; when the rest of the school returned there were rumors that he'd been petrified, John was sure Mycroft would have ultimately preferred petrification to his current predicament. 

When Greg told Sherlock that his brother was in the hospital wing Sherlock was genuinely bewildered and spent a great amount of time loitering near the hospital without ever visiting Mycroft, and when Mycroft was finally released Sherlock avoided him like a plague.

John would never understand siblings.

When Greg found that Mycroft was keeping his get-well card from Lockhart pressed between the pages of _Wandering With Werewolves_ , John reacted with utmost wisdom, letting Greg reap the rewards of his teasing alone lest Mycroft hex him too.

John wasn't sure he understood his friends either.

Greg and Mycroft joined him in their dormitory soon after, Greg sporting blindingly pink feathers in place of his usual silvery hair and limping slightly. 

"Gregory said you'd found something of interest?" Mycroft asked, smirking contentedly.

"Er, yes, in Moaning Myrtle's bathroom..." John rubbed his hand over his face, then turned to his trunk. "A diary, but it's empty. Greg recognized the name from the trophy room--the bloke was student here fifty years ago."

Mycroft raised an eyebrow, taking the diary from John carefully.

"John reckons it might say something about the Chamber of Secrets, I reckon it's blank, and that somebody tried to chuck it for a reason," said Greg, flopped on John's bed and molting pink feathers all over his pillow.

Mycroft frowned, turning the diary over in his hands and noting it's muggle origins, "The question is _why_ someone tried to dispose of it."

"I'd like to know what Riddle did to win that award--special services to Hogwarts, a bit vague, isn't it?" John looked over to Greg, "Hey, would you get your feathers off _my_ bed?"

"Could have been anything," Greg shrugged, collecting his feathers. "Could've been he got thirty OWL's or saved a teacher from the giant squid. Maybe he murdered Myrtle, that would've done everyone a favor."

Mycroft blinked slowly, an idea forming even as John spoke.

"Or, maybe, he caught whoever opened the Chamber last time."

Greg froze, a bundle of pink feathers in his arms. "But the diary's blank... There's nothing written in it, even if you were right we've not got any _evidence_."

John frowned, they were back to square one again. Mycroft looked pensive as he flipped slowly through the pages of the diary, until he glanced up to see Greg artfully decorating his four poster with bright pink feathers and let out an unearthly squawk.

John sighed.

Several days later Valentine's day descended upon the castle like a lurid pink, purple, and red, heart infested, storm with Professor Lockhart at it's confetti drenched center.

Mycroft had the nerve to _giggle_ , though thankfully Greg looked as perturbed and disgusted as John.

"Myc, please, for the love of Merlin, tell me _you_ weren't one of the lunatics who sent him a card!" 

Mycroft became suspiciously enthralled by the contents of his bag as they left the Great Hall.

It was difficult to say whether the day got worse or better later on--except for John, who found that the afternoon was easily the most entertaining thing to happen since Mycroft stopped coughing up the occasional hair ball.

"Oi! You there! You're Gregory Lestrade?" One of the "cupid" dwarves shouted up at Greg during their break.

"Er, who's asking?" 

"I've got a singing valentine for a Gregory Lestrade," the dwarf growled--as happy about the ordeal as Greg seemed to be.

"Er, no, probably not me then," Greg sidestepped quickly, hiding behind John uselessly, as John was half a head shorter.

The dwarf was not so easily discouraged, grabbing John's bag to pull him out of the way--not caring in the least as he tore it enough to send John's things everywhere, a bottle of ink shattering all over his books.

"Hey! That's--dammit, Greg, just get it over with!"

John crouched to collect his things and Mycroft held onto Greg as the dwarf began to sing badly:

" _His eyes are as brown as chocolate frogs,_  
His hair silver like snow under moonbeams,  
I wish he was mine, he's really divine,  
The slightly dim, but ardent, defender of dreams."

From where John was crouched on the ground--struggling to contain his laughter--he could see Sherlock, standing in the crowd that had assembled, biting his lips nervously with two spots of pink high on his cheeks. He noticed John staring, diary in one hand, and his eyes narrowed before he ran off.

As the crowd dispersed--none of _them_ holding in their amusement--Mycroft bent down to gather the last of John's ink covered things, spelling spilled ink away from _The Standard Book of Spells, Year Two_ with a strange grimace. Greg was where Mycroft had left him, standing with his mouth ajar.

"That was from _Sherlock_ ," John said as he stood, diary still in hand.

Greg shook his head, "Yeah, 'slightly dim' sort of gave it away."

"He has a crush on you," John grinned.

Greg forced a laugh, "I don't know if it's a crush, so much as he finds me bearable."

"To Sherlock, the two may be the same," Mycroft said, rolling his eyes and returning John's bag, repaired.

"Thanks, Mycroft--whatever it was, I'm remembering it forever, 'his eyes are as brown as chocolate frogs,' brilliant."

Greg was red to the tips of his ears.

"I rather enjoyed 'his hair silver like snow--'"

Mycroft dodged a half-hearted punch as John leaned against the wall, giggling.

"I will feed you both to the squid--what did I ever do to deserve such lousy friends?" Greg complained to a suit of armor, it shrugged in response.

"John..." Mycroft had noticed the diary John hadn't replaced in his bag.

"Yeah?" John was still grinning broadly.

"The diary--did you vanish the ink?"

John frowned, pushing off the wall as he paged through the diary, empty as ever, even after an inkwell had broken over it.

"No, I don't know the spell," John looked up at. Mycroft tilted his head slightly.

"I have an idea, but it will have to wait until tonight. We'll meet in the dorm after your quidditch practice."

When John came back from his journey inside the diary, he was white as a ghost.

"It was Hagrid."

**Author's Note:**

> As a nod to Greg's knowing Sherlock for five year before meeting John in ASiP, I've decided that Greg befriends Sherlock early on while John just sees him as the reclusive and strange younger brother to Mycroft. And it makes an adorable sort of sense that Sherlock would decide to have a "crush" on the incredibly friendly Gregory Lestrade who goes out of his way to be nice to a lonely Sherlock who feels abandoned by his big brother. And because it'll annoy Mycroft. He'll get to not recalling Greg's name eventually too. Character development and all.
> 
> I'm really not a Johnlock shipper (which is allowed, and I don't hate on it), so if that happens, it'll be a ways in. Honestly, I think it'd be entertaining to explore John/Jim as a Drarry deal... But they're still kids. Actual pairings will absolutely not happen until fourth year. 
> 
> That was longer than expected.


End file.
